A wheel bearing apparatus that supports a wheel of a vehicle relative to a suspension apparatus and incorporates a wheel speed detecting apparatus to detect a rotational speed of a wheel of a vehicle to control the anti-lock braking system (ABS) is known. Such a bearing apparatus generally includes a sealing apparatus between an inner member and an outer member. The inner and outer members are rotatable relative to each other via rolling elements (balls). A magnetic encoder with magnetic poles alternately arranged along its circumference is integrated into the sealing apparatus. A wheel speed detecting sensor is provided to detect the variation in magnetic poles of the magnetic encoder according to the rotation of the wheel.
The wheel speed sensor is usually mounted on a knuckle after the wheel bearing apparatus is mounted on the knuckle to form a suspension apparatus. Recently, however, a wheel bearing apparatus incorporated with a wheel speed detecting apparatus has been proposed. A wheel speed detecting sensor is self-contained within the wheel bearing in order to reduce the size of the wheel bearing apparatus as well as to eliminate troublesome air gap adjustment between the wheel speed sensor and the magnetic encoder.
An example of a prior art wheel bearing apparatus incorporated with a wheel speed detecting apparatus is shown in FIG. 5. This wheel bearing apparatus incorporated with a wheel speed detecting apparatus includes a detachably combined unit. The unit includes a wheel hub 55, a double row rolling bearing 50, and a constant velocity universal joint 61. The double row rolling bearing 50 has an outer member 51, an inner member 52, and double row balls 53, 53. The outer member 51 is integrally formed on its outer circumference with a body mounting flange 51b. The flange 51b is mounted on a knuckle 54 to form a portion of a suspension of a vehicle. The outer member 51, on its inner circumference, has double row outer raceway surfaces 51a, 51a. 
The inner member 52 includes the wheel hub 55 and an inner ring 56 secured on the wheel hub 55. The wheel hub 55 is formed on one end with a wheel mounting flange 55d, to mount a wheel (not shown). The wheel hub 55 outer circumference has one inner raceway surface 55a opposing one of the double row outer raceway surfaces 51a, 51a. A cylindrical portion 55b extends from the inner raceway surface 55a. The cylindrical portion 55b inner circumference includes a serration 55c for torque transmission.
The inner ring 56 is formed on its outer circumference with the other inner raceway surface 56a opposite to the other of the double row outer raceway surfaces 51a, 51a. The inner ring 56 is press-fit onto the cylindrical portion 55b of the wheel hub 55, via a predetermined interface. The inner ring 56 is axially secured on the cylindrical portion 55b by a caulked portion 57. The caulked portion 57 is formed by radially outwardly plastically deforming the end of the cylindrical portion 55b. 
Double row balls 53, 53 are contained between the double row outer raceway surfaces 51a, 51a and the inner raceway surface 55a, 56a, respectively, of the wheel hub 55 and the inner ring 56. The balls are rollably held by cages 58, 58. In addition, seals 59, 60 are mounted in annular openings formed by the outer member 51 and the inner member 52. The seals 59, 60 prevent leakage of grease contained in the bearing and the entry of rain water or dusts from the outside.
The constant velocity universal joint 61 includes an outer joint member 62, joint inner ring 63, a cage 64 and torque transmitting balls 65. The outer joint member 62 has a cup-shaped mouth portion 66, a shoulder portion 67, and a shaft portion 68. The shoulder portion 67 forms a bottom of the mouth portion 66. The shaft portion 68 axially integrally extends from the shoulder portion 67. The shaft portion 68 is formed, on its outer circumference, with a serration 68a to engage the serration 55c of the wheel hub 55. An outer screw thread 68b is formed on the end of the serration 68a. The outer joint member 62 is inserted into the wheel hub 55, via serrations 55c, 68a for torque transmission. The wheel hub 55 and the outer joint member 62 are united by a securing nut 69 fastened onto the outer screw thread 68b. 
As shown in FIG. 6, the seal 60 is formed by a so-called pack seal. It is a combination of a first sealing ring 70 and a second sealing ring 71. The first sealing ring 70 is mounted on the outer member 51. The first sealing ring 70 has a metal core 72 with a substantially L-shaped cross-section. A sealing member 73 is mounted on the metal core 72. The sealing member 73 includes a main lip 73a and an auxiliary lip 73b. 
The second sealing ring 71 is mounted on the inner ring 56. The second sealing ring 71 has a metal core 74 with a substantially L-shaped cross-section. A radial lip 75 is mounted on the metal core 74. A pulser ring 76 is mounted on the second sealing ring 71. The pulser ring 76 includes a metal core 77 with a substantially C-shaped cross-section. The pulser ring 76 is fit onto the metal core 74. A multi-pole magnet rotor 78 is mounted on the metal core 77. The multi-pole magnet rotor 78 is formed of rubber or resin mingled with magnetic powder. It has N and S poles arranged alternately along its circumferential direction. It is bonded onto the metal core 77 via vulcanized adhesion. The multi pole magnet rotor 78 is polarised from a radial direction.
The metal core 72 of the first sealing ring 70 is covered by a sensor holder 79 along its entire outer circumference. The sensor holder 79 is made of non-magnetic resin such as polyphenylene sulfide (PPS). A magnetic sensor 80 is embedded in the sensor holder 79. A female connector 81 electrically connects the magnetic sensor 80. A harness (not shown), of an electronic circuit on a body of vehicle, is integrally molded with the sensor holder 79 at a predetermined circumferential position so that it projects radially outward.
Accordingly the pulser ring 76 can be prevented from being contaminated by dusts etc. by the radial lip arranged outside of the pulser ring 76. In addition, since the pulser ring 76 is isolated from the balls 53 and the inner and outer raceway surfaces by the main lip 73a of the first sealing ring 70 and the auxiliary lip 73b. Thus, it is possible to prevent the pulser ring 76 from being contaminated by abraded metal powder generated by rolling of the balls. Accordingly, this keeps the detecting accuracy. (See, Japanese Laid-open Patent Publication No. 98332/2005)
In the prior art wheel bearing apparatus incorporated with a wheel speed detecting apparatus, the female connector 81 is formed to project radially outward and vertically to the axis of the bearing. Thus, a strong pressing force is applied to the first sealing ring 70, the magnetic sensor 80, via the connector 81, and thus the sensor holder 79 during connection of the connector 81. Accordingly, the positional accuracy of the first sealing ring 70 and the magnetic sensor 80 tends to be diminished. Additionally, the sensor holder 79 itself, made of plastic resin, may be broken.